This invention relates to conveyors, and more particularly to totally or partially enclosed tubular conduit conveyors which move the conveying material by power driven flights within the conduit.
Most commonly, such tubular conveyors operate on the "endless chain" principle and generally comprise a complete loop conveying path wherein a charging station or stations are provided in a certain area of the conveying loop, and wherein a discharge station is provided at another portion of the conveying loop. Typically, the conduits of completely, totally enclosed tubular conveyors have (1) a liquid tight conveyor casing, usually of a round, square or rectangular cross section, (2) an endless chain mounted therein, and (3) generally round, square or rectangular planar conveyor plates or flights centrally secured to the chain and oriented generally perpendicularly to the conveyor casing walls.
Totally or partially enclosed tubular conveyors are commonly used for transporting dry granular materials, mill scale and metal chips from metal working processes, and sticky or viscid materials such as filter cake, paint, grinding sludge, and sewage sludge. Though tubular conveyors work well with non-sticky or non-viscid materials, the use of tubular conveyors with sticky or viscid materials has certain drawbacks. Such drawbacks are also experienced with other types of conveyors.
Specifically, viscid material adheres to the conveyor flight plates in large clumps or globs and much of the material fails to drop off of the flights at the discharge station. The viscid material remaining on the flights continues around through the return leg of the conveying loop back to the charging station or stations. Thus, at the charging station, the amount of material that can be introduced into the conveyor is reduced by the amount of viscid material that is still stuck to the conveyor flights and is recirculating through the conveyor. Obviously, this (1) reduces the total conveying efficiency, (2) adds an increased conveying load upon the conveyor drive system and thus requires more energy for conveyor operation, and (3) leads to increased abrasive and scraping wear in the return portion of the conveyor.
It would be desirable to provide a flight conveyor for use with viscid materials which has an assembly or mechanism for removing or scraping the viscid material from the flights at the discharge station. It would also be desirable that such a flight scraper assembly operate simply and efficiently and preferably be driven by the conveyor flights themselves so that the scraper assembly would not require a separate drive or power source and so that it would not require any complex transmission and/or gear drive mechanisms.